A liquid or dry compound used to reduce the pH of swimming pool or spa water. See Sodium bisulfate.

Microscopic plant-like organisms that contain chlorophyll. Algae are nourished by sunlight (carrying out photosynthesis). They are introduced by rain and wind and grow in colonies, producing nuisance masses. These organisms include green, blue-green or black, brown, and yellow-green (mustard) algae. Pink/red colored algae-like organisms exist but are bacteria and not algae. There are 21,000 known species of algae.

A natural or synthetic substance used for killing, destroying or controlling algae. (Also spelled Algicide)

The amount of bicarbonate, carbonate or hydroxide compounds present in water solution. See also Total Alkalinity.

An aluminum sulfate compound used to cause suspended solids in the water to congeal into filterable masses (flocculate).

A term used in rating chlorine-containing products as to their total oxidizing power. (also see free available chlorine.)

The process of thoroughly cleansing the filter medium and/or elements by the reverse flow of water through the filter.

The addition of a sufficient amount of chlorine to water to destroy the combined chlorine present in the water. Generally considered to be 10 times the free available chlorine (FAC) level currently measured.

A method of putting granular or powdered chemicals into a pool by spreading them widely over the surface of the water.

A chemical element that exists as a liquid in its elemental form or as a part of a chemical compound which is an oxidant and a biocidal agent used to disinfect pool or spa water.

A soluble white salt used to raise the calcium hardness of pool and spa water.

A solid white form of inorganic chlorine found in both granular and tablet forms, it has a pH of approximately 11 and is 65.70 percent available chlorine.

A deck structure that relies on the pool structure for support. Free-Standing type: A deck structure that that does not rely on the pool structure for support.

A depth, pleated or surface-type filter component with fixed dimensions and designed to remove suspended particles from water flowing through the filter.

A filter that utilizes a porous element that acts a s filter medium. The cartridge is disposable.